#include <gtk/gtk.h>

/* This is a callback function. The data arguments are ignored
 * in this example. More on callbacks below.
 */
static void print_hello (GtkWidget *widget,
        gpointer   data) {
    g_print ("Hello World\n");
}

static gboolean on_delete_event (GtkWidget *widget,
        GdkEvent  *event,
        gpointer   data) {
    /* If you return FALSE in the "delete_event" signal handler,
     * GTK will emit the "destroy" signal. Returning TRUE means
     * you don't want the window to be destroyed.
     *
     * This is useful for popping up 'are you sure you want to quit?'
     * type dialogs.
     */
    g_print ("delete event occurred\n");
#ifdef DESTROY_ON_DELETE
    return FALSE;
#else
    return TRUE; //终止本轮信号回调
#endif //QUIT_ON_DELETE

}

int main (int  argc, char *argv[]) {

    /* GtkWidget is the storage type for widgets */
    GtkWidget *window;
    GtkWidget *button;

    /* This is called in all GTK applications. Arguments are parsed
     * from the command line and are returned to the application.
     */
    gtk_init (&argc, &argv);

    /* create a new window, and set its title */
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW (window), "Hello");

    /* When the window emits the "delete-event" signal (which is emitted
     * by GTK+ in response to an event coming from the window manager,
     * usually as a result of clicking the "close" window control), we
     * ask it to call the on_delete_event() function as defined above.
     *
     * The data passed to the callback function is NULL and is ignored
     * in the callback function.
     */
    g_signal_connect (window, "delete-event", G_CALLBACK (on_delete_event), NULL);

    /* Here we connect the "destroy" event to the gtk_main_quit() function.
     * This signal is emitted when we call gtk_widget_destroy() on the window,
     * or if we return FALSE in the "delete_event" callback.
     */
    g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);

    /* Sets the border width of the window. */
    gtk_container_set_border_width (GTK_CONTAINER (window), 10);

    /* Creates a new button with the label "Hello World". */
    button = gtk_button_new_with_label ("Hello World");

    /* When the button receives the "clicked" signal, it will call the
     * function print_hello() passing it NULL as its argument.
     * The print_hello() function is defined above.
     */
    g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

    /* The g_signal_connect_swapped() function will connect the "clicked" signal
     * of the button to the gtk_widget_destroy() function; instead of calling it
     * using the button as its argument, it will swap it with the user data
     * argument. This will cause the window to be destroyed by calling
     * gtk_widget_destroy() on the window.
     */
    g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_widget_destroy), window);

    /* This packs the button into the window. A GtkWindow inherits from GtkBin,
     * which is a special container that can only have one child
     */
    gtk_container_add (GTK_CONTAINER (window), button);

    /* The final step is to display this newly created widget... */
    gtk_widget_show (button);
    /* ... and the window */
    gtk_widget_show (window);

    /* All GTK applications must have a gtk_main(). Control ends here
     * and waits for an event to occur (like a key press or a mouse event),
     * until gtk_main_quit() is called.
     */
    gtk_main ();
    return 0;
}
